低合金钢(10MOWVNb)中γ/α相界面沉淀及位错碳化物

本文选用薄晶体透射电镜法及x射线衍射定量相分析法研究10MOWVNb抗氢钢在γ→α转变过程中碳化物析出规律,观察到碳化物主要以相间沉淀,纤维状生长及位错上析出三种方式形成,通过对碳化物固溶温度估算及x射线定量相分析,进一步阐明在所给条件下析出的碳化物主要为V_4C_3。 运用晶界相对入射电子束倾斜能显示二维晶界面特征方法,验证了Honeycombe提出的有关相间沉淀碳化物生核、长大的观点。 文中对高温回火过程中,碳化物可能以恒温相间沉淀方式析出进行了初步探讨。     

相间沉淀钢的合金设计与开发

设计与开发了四种成分的新型相间沉淀钢，其σｓ＞５００ＭＰａ，室温ＣＶＮ＞１７０Ｊ，截面尺寸在１５０ｍｍ范围内可获得均匀的组织与性能，可直接在轧制或正火态下应用。     

相间沉淀用钢概述

在材料科学领域，钢铁材料正受到其他材料的冲击和挑战，只有不断研制新品种，适应新形势对材料的要求，降低材料成本，才能使钢铁材料具有竞争力。在此前提下，相间沉淀用钢应运而生，前景看好。     

面心立方基体内B2结构沉淀相间的界面结构

从面心立方基体的对称性出发，我们确定了该基体内固态沉淀反应所致Ｂ２结构沉淀相之间的界面取向；基于稳定界面结构应具有最低能量的考虑，提出了几种可能的沉淀相间界面结构模型；实验观察表明，Ｎｉ－Ｂｅ合金中沉淀相间界面取向满足对称性要求，β／β界面结构跟自由β相的＜１１０＞｛１１２｝孪晶界面相同，但界面附近存在应变场。     

Ti-MO低碳超高强钢中相间析出强化

在不同温度下对Ti-Mo低碳钢进行等温转变,对热轧板进行力学性能检测,利用扫描电镜、透射电镜、选区电子衍射等方法进行组织观察,同时分析了相间析出粒子的形貌、尺寸和分布规律.结果显示,随着等温温度降低,钢的强度提高,延展性降低,屈强比增大.在透射试样中观察到两种不同形态分布的相间析出碳化物:平面型相间析出和曲面型相间析出.相间析出碳化物的平均直径为4.30nm,平均纵横比为1.375.在650℃等温保温1 h时,相间析出强化对铁素体相强度的增量在400MPa以上.     

铌微合金化钢中热形变奥氏体的再结晶与沉淀过程研究

本文对10MnNb钢热形变奥氏体的再结晶和沉淀过程进行研究,并与16Mn钢作对比,以判别铌的影响。铌的微量添加使形变奥氏体的动态回复与再结晶过程得到延缓。无铌钢动态再结晶的表现激活能为30.4kcal/mole,而含铌钢则为74.9kcal/mole。铌的添加亦明显地阻碍热形变奥氏体的静态回复与再结晶;在800℃时,含铌钢的静态再结晶几乎完全被抑制。形变奥氏体的再结晶有两种方式:一种是应变诱导晶界迁移,但不是主要的方式,主要的是通过原奥氏体晶界或退火孪晶界上形核并长大。形变奥氏体中的应变诱导碳化物沉淀和未形变奥氏体中碳化铌的静态沉淀研究表明:0.357的应变量可使碳化物沉淀过程加速两个数量级。再结晶过程改变了沉淀粒子的尺寸与分布。这是由于再结晶前沿界面引起沉淀粒子快速粗化所致。本文对再结晶和沉淀过程的交互作用的微观机制进行了探讨。铌抑制再结晶过程的原因是由于溶质原子对晶界或亚晶界的拖曳效应以及碳化铌沉淀粒子对这些晶界的钉扎作用。根据铌对热形变奥氏体再结晶与沉淀过程的影响规律,对优选10MnNb钢的控制轧制工艺参数作了分析并提出了建议。     

电炉-CSP工艺生产HSLC钢的研究与开发

介绍了HSLC钢的力学性能、成分和纯洁度控制,讨论了HSLC钢的强化机理.结果表明,在σ8≤450MPa条件下,珠钢电炉-CSP工艺生产的HSLC钢的力学性能与国外同类钢相当.提出了HSLC钢的成分控制要点,开发了电炉终点碳控制和低氧控制技术,发现了低碳钢中存在纳米硫化物、氧化纳、氮化物和碳化物.与HSLA钢类似,HSLC钢亦具有沉淀强化机制,纳米铁碳化物应是主要沉淀强化相.     

钢在(γ+K)二相区超塑变形中沉淀碳化物的研究

钢在A_(c1)温度以上(γ+K)二相区的超塑性交形过程中,在奥氏体内有M_3C型碳化物颗粒沉淀,其尺寸为60～100A。碳化物的沉淀影响超塑变形过程及超塑变形后钢的力学性能。     

高强度含铜钢奥氏体连续冷却转变产物的强韧性

研究了高强度含铜钢HSLA80和HSLA100奥氏体连续冷却转变产物的强度和韧性随冷却速率的变化规律,探讨了连续冷却过程中形成的Cu沉淀的特征和熟化规律.在Gleeble3800热模拟试验机上进行0.1℃·s-1至20℃·s-1的连续冷却实验,利用扫描电镜和透射电镜分析了显微组织和Cu沉淀.结果表明,随冷却速率提高,HSLA80的连续冷却转变组织由多边形铁素体向块状铁素体和贝氏体转变,在冷速0.1~1℃·s-1范围内Cu发生沉淀,两者综合作用造成随冷却速率提高钢的硬度分阶段变化,而韧性逐渐提高;HSLA100的连续冷却转变组织以贝氏体为主,且不发生Cu的沉淀,随冷却速率提高钢的硬度基本保持不变,但韧性发生剧烈变化.连续冷却过程中形成的Cu沉淀在等温过程中的熟化符合Ostwald熟化规律,半径随时效时间t1/3变化.     

低碳超级钢中氧硫氮的控制及其对钢组织性能的影响

对低碳超级钢ZJ330薄板坯连铸连轧过程中氧化物、硫化物析出进行了热力学分析 ,对钢中氧、硫、氮的控制及其对钢组织性能的影响进行了讨论 ,指出 :纳米级氧化物、硫化物析出导致铝镇静钢中晶粒细化 ,通过细晶强化和沉淀强化提高钢的强度 ;组织均匀、硫含量低及硫化物尺寸细小是钢力学性能各向同性的原因 ;钢中铝含量的最佳控制范围有待进一步研究     

Nb-V低碳微合金钢等温淬火过程析出行为

利用透射电镜和纳米压痕仪对Nb-V低碳微合金钢中纳米碳化物的析出行为进行研究.研究结果表明,在700℃等温60min试样中,可同时观察到相间析出和弥散析出,在其余试样中均未观察到相间析出,此规律可以通过相变过程中的扩散准则和台阶机制来解释.另外,纳米压痕结果显示在600℃等温20min试样中,平均硬度为3.87GPa,650℃等温20min试样中,平均硬度为4.10GPa,且通过TEM观察可以看出,650℃等温20min中试样析出物数量密度较大且分布均匀.利用Ashby-Orowan机制对析出强化量进行计算,可以得出在650℃等温20min试样中,析出强化对整个屈服强度的贡献量可以达到110MPa.     

短纤维增强橡胶密封复合材料纵向拉伸模量的预测方法

摘要： 建立了含界面相、纤维和基体的短纤维增强橡胶（SFRR）密封复合材料纵向拉伸模量的预测模型,采用Mori Tanaka方法得到了SFRR的纵向拉伸模量的预测公式,将其计算结果与试验数据进行对比;同时,探讨了纤维体积分数、界面相的厚度和模量对复合材料纵向拉伸模量的影响.结果表明：纵向拉伸模量预测模型的计算值与试验值较吻合,其最大相对误差为11.2%;SFRR的纵向拉伸模量随着纤维体积分数的增加而增大;界面相模量对SFRR纵向拉伸模量的影响显著,当界面相模量小于基体模量时,SFRR的纵向拉伸模量随着界面相厚度的增加而减小;当界面相模量大于基体模量时,SFRR的纵向模量随着界面相厚度的增加而增大.     

500kV输电线路新型防舞金具试验

 减振防舞阻尼弹簧相间间隔棒作为一种新型防舞金具,通过弹簧、橡胶和重球系统吸收导线振动时的能量达到防舞的目的。运用导线疲劳振动试验系统,对安装普通和减振防舞阻尼弹簧相间间隔棒的两相六分裂导线进行模拟舞动试验。稳定时对比子导线垂直和水平方向的位移。结果表明,相同条件下安装减振防舞阻尼弹簧相间间隔棒时导线垂直和水平方向的位移都小。由此验证,减振防舞阻尼弹簧相间间隔棒具有较好的防舞效果,是一种非常实用的防舞金具。     

华北冬小麦作物气候干旱指数研究

作为农业干旱指标,降水距平百分率未考虑底墒作用,不同发育期水分对产量影响不同.利用降水距平百分率指数构建了华北冬小麦作物气候冬小麦干旱指数.该指数将冬小麦不同发育阶段的水分产量反应系数应用到降水距平干旱指数中,同时量化底墒对冬小麦生长发育过程中起到的重要作用.通过对河南省卢氏县冬小麦历年干旱和减产率进行计算和分析,结果表明,作物气候指标负距平百分率和减产率的相关性明显高于降水负距平百分率和减产率的相关性.作物气候冬小麦干旱指数在评估冬小麦干旱时要优于降水距平百分率,将作物和气候干旱相结合能更准确地评估冬小麦干旱,弥补降水距平百分率作为农业干旱指数只涉及气候干旱的不足.     

Further mechanism of α/β interphase boundary evolution and dynamic globularization of Ti–5Al–2Sn–2Zr–4Mo–4Cr at elevated temperature deformation

The evolution characterization of the α/β interphase boundaries of the isothermally compressed Ti–5Al–2Sn–2Zr–4Mo–4Cr with lamellar microstructure was carried out via electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). The effect of the α/β interphase boundary evolution on the dynamic globularization was discussed, and the nucleation model for the β recrystallized grain at the cusp of α lath in the late stage of deformation in terms of the classic nucleation theory was established. The mean α/β interface deviation angle from Burgers orientation relationship (BOR) increased continuously up to 18.9° with the increasing strain from 0.1 to 0.5, which was dominated by the continuous dynamic recrystallization. Restoration of BOR between α and β phases at the strains of 0.7 and 0.9 occurred due to the occurrence of recrystallized α and β grains following BOR, which was rationalized by a nucleation model considering the stored energy of deformation provided the driving force for nucleation at the cusp of α lath. Loss of coherency of α/β interphase boundaries at a strain about 0.3 was responsible for accelerating the dynamic globularization of α lamellae since the energy of α/β interphase boundaries increased up to the maximum value when the non-coherent α/β interphase boundaries were formed. Restoration of coherency of α/β interphase boundaries due to the recrystallization nucleation in the late stage of deformation did not substantially affect the dynamic globularization since the α/α intraphase high-angle boundaries (HAGBs) were formed and the most α/β interphase boundaries were non-coherent.     

三相结构一维电子密度的相关函数

从结晶聚合物的三相结构出发,计算了线性电子密度相关函数,理论上得到了不变量和结晶层厚度和散射曲线的对应关系,并与G. R. Strobl等人从两相模型推广到三相模型得到的结论相比较,指出直接从两相推广到三相的不妥之处,修正了推广过程中的错误.从三相模型的相关函数图可以直接得到长周期、晶片厚度、不变量、过渡层厚度,但是晶片厚度、不变量与Strobl的定义有所不同.     

Analysis of the formation conditions and characteristics of interphase and random vanadium precipitation in a low-carbon steel during isothermal heat treatment

The characteristics of nanosized precipitates in steels depend on the heat-treatment parameters. The effects of characteristics of vanadium precipitates formed during isothermal heat treatment on the hardness of the ferrite matrix in low-carbon vanadium-alloyed steel were investigated through analysis of transmission electron microscopy images and microhardness measurements. The results show that, during isothermal holding in the temperature range from 675 to 750℃, only interphase precipitation occurs, whereas only random precipitation occurs in the ferrite matrix during holding at 600℃. Furthermore, during isothermal heat treatment between 600 and 675℃, both random and interphase precipitates occurred in the ferrite. Nanoscale vanadium carbides with different atomic ratios of vanadium (V) and carbon (C) were the dominant precipitates in the random and interphase precipitates. The sizes of random precipitation carbides were smaller than those of interphase ones. Also, the sample isothermally heat treated at 650℃ for 900 s exhibited a higher hardness with a narrower hardness distribution.     

Preparation,thermal stability and biocompatibility studies of gelatin-induced hydroxyapatite co-substituted with essential physiological trace elements

Gelatin-induced hydroxyapatite with combined substitution of essential physiological trace elements(G-FAP)was prepared by a precipitation method.Pure hydroxyapatite(HAP)and ion-substituted hydroxyapatite(FAP)were also prepared for comparison.The characteristics of the precipitated powders were determined using X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FT-IR),specific surface area measurement(SSA),X-ray fluorescence spectroscopy(XRF),and thermogravimetric(TG)analysis.The biocompatibility was also determined by an in vitro investigation with MC3T3-E1 cells.SEM and TEM results showed that the G-FAP powders were composed of dense aggregates of agglomerated whisker-like crystals of200–300 nm in length and 10–20 nm in width.XRD and FT-IR analyses indicated the formation of pure apatite phase,and the substituted ions and gelatin did not change the diffraction pattern of the precipitated powders.The SSAs of the precipitated powder were 64.741,72.492,and107.745 m2/g,for HAP,FAP,and G-FAP,respectively.XRF analysis showed that Na+,Mg2+,and F-were substituted into the crystal lattice.TG results showed a reduced thermal stability of the precipitated G-FAP powders,with an advanced phase transformation beginning at800°C and a serious phase transformation from hexagonal apatite phase to rhombohedral b-TCP phase at 1,200°C in comparison with HAP and FAP.In vitro biological tests showed non-cytotoxic effects for all powders.However,G-FAP stimulated the proliferation of MC3T3-E1 cells earlier than HAP and FAP.The present G-FAP will therefore be a promising primary biomaterial for bone regeneration,tooth filling,or as a coating for metal artificial limbs.     

小麦染色体和间期集缩染色质孔洞及内在结构的观察

对小麦根端分生组织进行常规电镜观察的结果表明：小麦染色体和间期集缩染色质中均存在孔洞，里面有由颗粒和纤维构成的、类似于骨架的结构，对有关染色体骨架和染色质骨架之间以及它们与核基质之间的相互关系进行了讨论。     

Cyclin synthesis drives the early embryonic cell cycle

We have produced extracts of frog eggs that can perform multiple cell cycles in vitro. Destruction of the endogenous messenger RNA arrests the extracts in interphase. The addition of exogenous cyclin mRNA is sufficient to produce multiple cell cycles. The newly synthesized cyclin protein accumulates during each interphase and is degraded at the end of each mitosis.